1. Field of the Invention
The present invention is directed towards new sulfamide compounds and methods of forming those compounds via ring-closing metathesis reactions carried out in the presence of a ring-closing catalyst such as an olefin metathesis catalyst (e.g., a Grubbs catalyst). The compounds have a number of uses including as inhibitors of enzymes such as HIV proteases.
2. Description of the Prior Art
Small peptides are excellent starting points for drug design because they have the potential to overcome the pharmacokinetic shortcomings of larger peptides, yet retain the desirable quality of molecular recognition. A number of dipeptides are currently being developed as novel pharmaceutical agents (see e.g., Blackburn et al., Bioorg. Med. Chem. Lett., 7:823-26 (1997); Schullek et al., Anal. Biochem., 246:20-29 (1997), each incorporated by reference herein). Unfortunately, even small peptides suffer from proteolytic instability which limits their use as drug candidates.
Peptide mimics have been developed that utilize the urea moiety as a non-hydrolyzable linker and/or a hydrogen bond acceptor. Further modifications to cyclic ureas have led to the generation of a new sub-class of biologically active compounds. A number of cyclic HIV protease inhibitors have been developed that incorporate ureas, sulfamides, and other urea surrogates as the central linchpin. In these cases, it has been shown that the H-bonding urea moieties may serve to replace the water molecule exclusive to the active site of HIV protease. Ring-closing metathesis (RCM) reactions have become a highly effective strategy for the construction of a number of important heterocyclic compounds (see e.g., Fu et al., J. Am. Chem. Soc., 115:9856 (1993), incorporated by reference herein) and constrained peptides (see e.g., Miller et al., J. Am. Chem. Soc., 117:5855-5856 (1995); Miller et al., J. Am. Chem. Soc., 118:9606-9614 (1996); Blackwell et al., Angew. Chem., Int. Ed., 37:3281-3284 (1998), each incorporated by reference herein).
Sulfamides are unique functional groups that have been exploited in the development of a number of novel pharmaceutical agents and synthetic ligands. Their ability to serve as urea surrogates have made them ideal functional groups for the development of novel peptidomimetics, while their chelating ability has made them ideal for the development of novel ligands for asymmetric catalytic reactions. This diverse set of properties has made them important targets in the development of new chemical entities.
Since its discovery as the causative agent of AIDS, considerable effort has been placed on understanding the biomolecular replicative process of the human immunodeficiency virus (HIV), with primary focus being placed on the inhibition of a key virally encoded protease enzyme of the pol gene. Many synthetic approaches to the inhibition of HIV protease are based on the synthesis of peptidomimetics which replace a key scissile amide bond by a non-hydrolyzable transition state isostere. This strategy has been employed to synthesize a number of novel nonpeptidal HIV protease inhibitors. Among the more effective peptidomimetics, the synthesis of cyclic ureas (see e.g., Lucca et al., Drugs of the Future, 23:987 (1998)), cyclic sulfamides (see e.g., Jadhav et al., Tetrahedron Lett., 36:6383 (1995)), hydroxyethylene/hydroxyethylamine isosteres (see e.g., Thomas et al., Biorg. Med. Chem. Lett., 4:2759 (1994)) have been reported.
The present invention is broadly concerned with new sulfamide compounds and methods of forming such compounds. In more detail, the compounds are represented by a formula selected from the group consisting of 
wherein:
each X is individually selected from the group consisting of oxygen, xe2x80x94NH, and xe2x80x94NOR1,
each R1 is individually selected from the group consisting of hydrogen, branched and unbranched alkyl groups (preferably C1-C18, more preferably C1-C8), branched and unbranched alkenyl groups (preferably C2-C18, more preferably C2-C8), branched and unbranched alkynyl groups (preferably C2-C18, more preferably C2-C8), allyl groups, acyl groups (preferably C2-C18, more preferably C1-C8), aryl groups (preferably C6-C12), 2-15 mer peptides, and benzyl groups;
each R2 is individually selected from the group consisting of hydrogen, substituted and unsubstituted amino acid side chains, and 2-15 mer peptides; and
each R3 is individually selected from the group consisting of hydrogen, xe2x80x94OH, and xe2x80x94NHR1, with R1 being as defined above.
Preferably at least one R2 group comprises an amino acid side chain selected from the group consisting of 
wherein each R4 is individually selected from the group consisting of hydrogen, branched and unbranched alkyl groups (preferably C1-C18, more preferably C1-C8), branched and unbranched alkenyl groups (preferably C2-C18, more preferably C2-C8), branched and unbranched alkynyl groups (preferably C2-C18, more preferably C2-C8), allyl groups, aryl groups (preferably C6-C12), acyl groups (preferably C2-C18, more preferably C2-C8), and benzyl groups.
Particularly preferred compounds according to the invention are those selected from the group consisting of 
wherein each R2 is individually selected from the group consisting of xe2x80x94CH3, xe2x80x94CH(CH3)2, xe2x80x94CH2CH(CH3)2, and xe2x80x94CH2Ph.
The inventive compounds are formed by reacting a template sulfamide compound which comprises an opened-ring structure (i.e., a partially-formed ring comprising at least half, but not all of the sides necessary to form a cyclic compound) with a ring-closing catalyst to yield the closed-ring phosphonamide compound. Preferred ring-closing catalysts are olefin metathesis catalysts such as Grubbs catalysts (see e.g., U.S. Pat. Nos. 6,048,993, 5,917,071, 5,750,815, 5,710,298, 5,342,909, and 5,312,940, each incorporated by reference herein) as well as those disclosed by the following references, each also incorporated by reference herein: Matthias, Org. Ltrs., 1(6):953-56 (1999); Schrock, Macromolecules, 29(19):6114-25 (1996); Zhu et al., J. Amer. Chem. Soc., 121(36):8251-59 (1999); Alexander et al., J. Amer. Chem. Soc., 120(16):4041-42 (1998); and Kingsbury et al., J. Amer. Chem. Soc., 121(4):791-99 (1999).
Particularly preferred Grubbs catalysts are those selected from the group consisting of 
Preferred template structures comprise an allylated sulfamide, with particularly preferred template structures being those selected from the group consisting of 
wherein:
each X is individually selected from the group consisting of oxygen, xe2x80x94NH, and xe2x80x94NOR1;
each R1 is individually selected from the group consisting of hydrogen, branched and unbranched alkyl groups (preferably C1-C18, more preferably C1-C8), branched and unbranched alkenyl groups (preferably C2-C18, more preferably C2-C8), branched and unbranched alkynyl groups (preferably C2-C18, more preferably C2-C8), allyl groups, acyl groups (preferably C6-C18, more preferably C1-C8) aryl groups (preferably C6-C12), 2-15 mer peptides, and benzyl groups; and
each R2 is individually selected from the group consisting of hydrogen, substituted and unsubstituted amino acid side chains, and 2-15 mer peptides.
Preferably the reacting step is carried out at a temperature of from about 15-80xc2x0 C., and more preferably from about 30-55xc2x0 C. Furthermore, the reacting step should be carried out in a solvent system comprising a solvent selected from the group consisting of toluene, benzene, chlorobenzene, dichlorobenzene, methylene chloride, dimethoxyethane, methanol, water, and mixtures thereof. Preparing the ringed sulfamide compounds according to the inventive methods should result in a yield of those compounds of at least about 70%, and preferably at least about 90%, wherein the theoretical yield is taken as 100%.
It will be appreciated that the inventive methods allow for the synthesis of a wide array of both symmetric and unsymmetric cyclic sulfamide compounds. Furthermore, the inventive methods allow for preparation of, or selection of, templates having particular functional groups bonded thereto which are then readily formed into the desired sulfamide in a controlled and repeatable manner. Because the method can be adapted to form sulfamide compounds comprising one or more amino acid side chains or peptides bonded thereto, the inventive compounds can be used to inhibit HIV proteases, carbonic anhydrase, renin, and other enzymes. The inventive compounds may also be used as retroviral inhibitors, anti-inflammatory agents, bioadhesion inhibitors, and herbicides.